Do Opposites Attract? For Magnets, Yes. For People, Not So Much.

The idea that we're attracted to mates who look like one of our parents can be a little off-putting. But if you're not already in a relationship with someone who looks like your mom or dad, chances are very good that you will be soon.

Take a minute and think back on all the women you’ve dated. How many of them look–even just a little–like your mother? Probably more than you think (or than you’d like to admit). That may be a little off-putting to contemplate, but it’s nothing to be embarrassed about; we all do it. It may be politically incorrect to say so, but we’re biologically wired to like the people we spend the most time with. In our early years, that’s mom or dad. We trust them, and as we get older we have a tendency to see people who look like them as more trustworthy. And according to psychologist David Perrett, trustworthy develops into “mateworthy.” So if you’re not already in a relationship with someone who looks like your opposite-sex parent, chances are very good that you will be soon.

In a series of studies, Perrett and his colleagues discovered that when it comes to finding romantic partners, we’re most attracted to the features our opposite-sex parent had when we were born (unfortunately, there hasn’t been any research on gay couples and whether they’re attracted to features of the same-sex parent).

In one study, the researchers found that our romantic partners and opposite-sex parents are likely to share the same eye and hair color. In another study, Parrett and his team found that we’re even drawn to people who are the same age our opposite-sex parent was when we were born. Using computer graphic faces, “we found that women born to ‘old’ parents (over 30) were less impressed by youth, and more attracted to age cues in male faces than women with ‘young’ parents (under 30),” Perrett wrote in the study. “For men, preferences for female faces were influenced by their mother’s age and not their father’s age.”

The traits we seem most attracted to are more than just superficial. In one study, strangers were able to match photos of women with their mother-in-law “at a significantly higher rate than expected by chance.”

Nature Vs. Nurture: It’s Not So Simple

If you’re thinking that this sounds like we’re careening through our love life on some kind of biological autopilot, you’re right. Partly. There’s plenty of Nurture to go along with all that Nature.

A team of researchers at the University of Pécs in Hungary found that heterosexual individuals use their opposite-sex parent as a “template for acquiring mates” even if they were adopted or raised in a loving foster home. In addition, the relationship between the child and his or her opposite-sex parent played an important role.

Women who “rated their childhood relationships with their father highly” were much more likely to rate as “attractive” photos of men who resembled their father than were women who rated their father “less highly,” according to Agnieszka Wiszewska, lead author of a 2007 study published in the journal Evolution & Human Behavior. Similarly, women who “received more emotional support from their adoptive father were more likely to choose mates similar to the father than those whose father provided a less positive emotional atmosphere,” according to researcher Tamás Bereczkei.

Blueprint for Love?

Oh, and we’re not the only ones in the animal kingdom who are attracted to the familiar. Most of us have seen videos of “animal imprinting.” That’s when newborns—usually ducks or geese—happy follow around the first living thing they see, whether that’s their own mother, some other animal, or a human. (If you don’t know what I’m talking about, go to YouTube, search for “duckling imprinting,” and get ready to say “awwwww.”)

This type of cross-species nurture-based imprinting is nothing new. According to Keith M. Kendrick of the Babraham Institute in Cambridge, England, “Young male sheep raised from birth by female goats develop a social and sexual preference for goats when they mature … [T]he emotional bond between a mother and her male offspring, rather than other social and genetic factors,” he adds, “may irreversibly determine these species’ social and sexual preferences” (I know what you’re thinking–stop it right now).

Mirror, Mirror On The Wall… The Final Piece Of The Puzzle

Narcissus—the character from Greek mythology who fell in love with his own reflection—may have just been doing what we’re all wired to do: fall in love with ourselves. In fact, that may be exactly what’s happening when we’re (subconsciously) selecting mates who look like Ma or Pa. After all, they probably look a little like us, right?

If you’re a Justin Timberlake fan, you’ll recognize these slightly narcissistic lyrics from his love song “Mirrors.”

It’s like you’re my mirror

My mirror staring back at me

I couldn’t get any bigger

With anyone else beside of me

And now it’s clear as this promise

That we’re making two reflections into one

‘Cause it’s like you’re my mirror

My mirror staring back at me, staring back at me

Sounds a little creepy—and vaguely incestuous—doesn’t it?

Psychologists R. Chris Fraley of the University of Illinois and Michael Marks of New Mexico State University did several fascinating experiments aimed at figuring out why we find ourselves so enchanting. In one, Fraley and Marks divided a number of volunteers into two groups. The control group was to evaluate the sexual attractiveness of a number of images that were graphically designed composites of the features of various strangers. The second group saw similar images, except that up to 45 percent of the features were from the subject’s own face. The individuals in that group were more sexually attracted to the images that contained pieces of themselves than they were to the other images.

Here’s the kicker:

Fraley and Marks ran another experiment. This time they showed a new series of composite images to both groups. They told half that the images contained elements of their own face (although none of them actually did). The people who believed they were looking in part at themselves rated those images as less sexually attractive than did the volunteers who thought they were looking at randomly assembled faces.

The point? It could be Nature’s way of keeping us from taking our love for ourselves and those who look like us too far: When we’re aware of the connection, we feel a sexual aversion.